There is an arithmetic error in the example calculation (also in the original book). In step 13, equation 52: the actual result is 0.0139^(1/2) = 0.118 ft = 1.415 in.
This leads also to water gap of size: (1/2)(1.415-1.3875) = 0.5 * 0.0275 in = 0.01375 in.
There is an arithmetic error in the example calculation (also in the original book). In step 13, equation 52: the actual result is 0.0139^(1/2) = 0.118 ft = 1.415 in.
This leads also to water gap of size: (1/2)(1.415-1.3875) = 0.5 * 0.0275 in = 0.01375 in.